Add docker CI

[tux2000]

Summary

This PR adds a GitHub Actions workflow to automatically build and publish Docker images to Docker Hub whenever a new release is published.

Motivation

Currently, Docker images are apparently published manually and may lag behind official releases. This automation ensures Docker images stay in sync with tagged releases.

Details

• Trigger: release.published
• Tags Docker images using the release version
• Pushes to Docker Hub (umap/umap)
• Also publishes to GitHub Container Registry (ghcr.io) using the built-in GITHUB_TOKEN (no extra secrets required)

Requirements

Repository secrets must be configured:

• DOCKERHUB_USERNAME
• DOCKERHUB_TOKEN

Optional

We can also publish a latest tag if desired.

Note

I could not test this thoroughly to make sure it actually works to push to docker hub. Let me know if I should revise or test in some specific way.

[yohanboniface]

Thanks a lot @tux2000 !

I've two questions:

• this will build/push a new Docker image only for a new tag, correct ?
• we are about to move to Codeberg (git, issues/PR and CI), do you by chance know is this can be adapted there ? (We'll anyway keep a mirror here, so we could also still rely on Github for the Docker image)

[tux2000]

1. yes, this will build and push docker images on "releases" in Github. I think this is even a subset of tags only, but in any case it is based on a clear and manually defined version of the code
2. I dont have experience with codeberg CI so I dont know how to get equivalent functionality in place there, but I would assume that this should be possible